Spark-plug.



,Lmwmm G. L. BREWER.

SPARK PLUG.

APPLICATxoN FILED mmmz. i911.

Patented Dec. 11, 1917.

ma. /wwm amy 4 MWh/1 w titl Specification oi Letters Patent.

Application led March 22, wl?.

To all unioni it may concern:

ide it known that l, ,GOVERNOR lL. BREWER, e eitizen ot' the UnitedStates, residing :it ltilent City, in the county of lient and State oi.li/lichigsn, have invented certain new end useful improvements inSperkljlugs; and ll do hereby declare the following to be aa full,elettr, and exact description of the invention, such as will enableothers skilled in the ort to which it nppcrteins to 'make and use theseme.

This invention relates to spark plugs for igniting the intlainmablecharges of internal combustion engines by means of electricity; sind itconsists in the novel construction and combination of the portshereinafter iully described end eleinied.

in the drawings, Figure l is e longitudinel section through e spark plugconstructed `soeording to this invention. Fig. 2 is a side view of theplug turned trotted one-quarter from the position shown in Fig. l. Fig.3 is e eross-seotion, teken on the line m-m in Fig, l. A

rChe body portion 2 of the plug is adapted to be screwed into e cylinderin the usual wey. .du insulating sleeve 3 is secured in the body 2 bymeans ont e screwthreeded coller il. A lower spark stein 5 is secured inthe sleeve 3 by Ineens of nuts 6 which are screwed on the stern, sindwhich enable its position in the sleeve 'to be sdj usted longitudinelly.A stationery electrode 7 is secured to the bottom ot the plug body, undpreferebly consists of s steple-shsped piece of wire which extendserosswise under the bottom ond of the stem A screwthreaded coller 8 ofinsulating ineterisl is secured on the upper end portion ot' the stern 5between the upper end of the sleeve 3 and the upper nut, and thefristening collar flis made large enough to slip over it. tubularchamber 9 is provided, endv its lower end portion is screwed on thesmell coller 8. The insulating sleeve 3 has e projecting coller l0 etits middle part, and l2 are washers on opposite sides of this-collerwhich prevent the sleeve 'troni/being broken when it is cluinpedinpiece. y,

The tubular chamber 9 hes openings it Patented Deo, itt, tbtll't.

serial 1ro. 156,613.

on eech side which form sight holes, and e plug of insulating material'is secured in 1S, und secures the conducting wire 19vto it, and alsolocks it in position in the plu l5. The edjacent ends of the upper anlower stems 18 and 5 are arranged 'et the middle part of the sight tube,and form et spark gzip so that the sparks can be seen through the sightholes of the chamber.

The sparks seen through the sight holes show clearly when the device isworking properly, and the additional spark gap oper-- A thumb-nut 20 isscrewed on the upper projecting end portion of the stem* etes tointensify the action of the sparks of the lower spark gap by which theigni* tion of the iniiainmuble charge in the vcylinder is effected.

What l claim is:

ln e spark plug, e body portion provided.

with an electrode at its inner end, an insuluted lower spark sternsupported 1n the .said body portion, an externally screwthrefided collurot' insulating materiel' and st washer of insulating material secured atthe outer ond of the seid body portion, o tubular sight chamber havingits lower end screwed on the said collar und bearing on the said washer.u 'plug of insulating material screwed into the upper end of the sightchunnber1 un upper spark stein supported inV the suid plug and formingun upper spark gap with'the lower spark stem. andfzrglass sight tubeurrnuged in the sight chamber and clamped between the seid collar andplug and permitting the spark of the upper spark gap to be seen in thesight ehember.

ln testimony whereof l have eiiixed my signature.

ooveinton L. nenwnn,

